Current transfer system



July 16, 1940. c. LYNN 2,208,381

CURRENT TRANSFER SYSTEM Filed May 16, 1959 2 Sheets-Sheet l F I 40 9 22 42 24 7O 74 28 WITNESSES: INVENTOR 554 r C/arence Z Hf).

July 16, 1940. c. LYNN CURRENT TRANSFER SYSTEM Filed May 16, 1939 2 Sheets-Sheet 2 \9 WITNESSES: n 547% %LW% a Patented July 16, 1940 UNITED STATES PATENT, OFFICE CURRENT TRANSFER SYSTEM Vania Application May 16, 1939, Serial No. 273,866

Claims.

My invention relates, generally, to current transfer systems, and, more particularly, to a system for supplying current to the contact rolls of a steel strip heating device.

A known system for heat treating metal comprises pulling the metal in the form of a strip between two adjacent sets of rolls and passing current into the strip through one set of rolls, through the length of strip extending between the sets of rolls, and conducting it from the strip through the other set of rolls. The current must be conducted to the contacting rolls by means of brushes and slip rings. comparatively large currents are necessary to provide the desired resistance heating of the strip, and there is a very considerable friction load because of the large brush contact area necessary to carry such large currents.

In such a system, the contact rolls are not driven except by the strip as it is pulled through the rolls. At the high temperatures to which the strip is subjected, its yield point and tensile strength are so reduced from their normal values as to preclude the use of the pull on the strip to both drive the rolls and transmit the power for the brush friction load without serious stretching or breaking of the strip.

An object of my invention is to provide such metal heat treating systems as I have described hereinbefore with a current transfer system which shall function to supply current to the contact rolls without subjecting the strip to the brush friction load.

Another object of the invention is to provide a current transfer system which shall function to conduct current to a rotating device without subjecting the rotating device to the driving load of the current transfer system.

These and other objects and advantages of the 0 invention will be apparent from the following detailed description taken in connection with the accompanying drawings, in which:

Figure '1 is a plan view of a metal strip heat treating system embodying the principal features of the preferred embodiment of my invention;

Fig. 2 is an enlarged side elevation view, having some parts in section and others broken away, of one set of contact rolls and the current transfer system associated therewith embodying the principal features of my invention; and

Fig. 3 is a diagrammatic View of a control system for controlling the speed of the drive motors shown in Figs. 1 and 2.

In the practice of my invention, I provide a pair of current transferunits l0 and I2, as shown in Fig. 1, which function to conduct current from a generator M to the strip l6 which is to be heated. Each of the current transfer units comprises a pair of cooperating contact rolls l8 and 20, shown in Fig. 2, between which the strip I6 is drawn by any suitable means. Each of the rolls is provided with a plurality of conductors 22 which connect it to a slip ring 24 and a set of brushes B8. The brushes 68 of the transfer units are connected to opposite terminals of the generator M by any suitable means.

Each slip ring 24 is driven by a motor 28, thus relieving the strip [6 of the brush friction load. The motor 28 functions to rotate the slip ring 24 at substantially the same speed as its associated contact roll by means of the control system shown diagrammatically in Fig. 3. In this control system, the speed of the motor 28 is controlled by a rheostat 30 connected to control the field current of the motor and actuated in accordance with the relative angular displacement of the roll and its associated slip ring.

Each of the contact rolls is provided with identical current transfer apparatus and, therefore, the apparatus associated with only one of these rolls will be described. Like reference characters are applied to identical elements of structure in the drawings.

Referring again to Fig. 2, the rolls l8 and 20 are supported upon suitable bearings 32 and 34 which in turn are mounted in the housing 36, the rolls being so disposed as to bear upon the strip 16 and be rotated by the strip as it is pulled between them.

The ends of conductors 22 are suitably secured to a plate member 38 which is secured by means of a cap 40, shown in section, which may be screw threaded to the neck of the roll l8. The other ends of the conductors 22 are suitably secured to a plate 42 which is mounted upon the end of a shaft 44. A shaft 46 is secured to the plate 38 for rotation therewith coaxial with the roll 18, and extends into a bearing 48 mounted in the plate 42, as shown in the cut-away section of Fig. 2. The end of the shaft 46 is so supported by the bearing 48 as to permit relative rotation of the plate 42 and the shaft 46. The conductors 22 extend through and are spaced and supported intermediate their ends by discs 50 which are supported upon the shaft 46.

The shaft 44 is supported upon bearings 52 and 54 which in turn are mounted upon any suitable supports 56 and '58. The slip ring 24 is mounted upon the shaft 44 for rotation there-- with and in electrical conducting relation therewith by means of conducting collars 68.

A collar 62 of insulating material is mounted upon a suitable support 64 and has secured to it a brush yoke 66, on which are mounted the brushes 68 in cooperative relation with the slip ring 24.

The shaft 44 is driven by the motor 28 through the gear members I8 and I2 and a reduction gearing element 14. The motor 28 is mounted upon any suitable supporting elements 16.

A rheostat resistance element I8 is secured to the disc 42 in any suitable manner coaxial with the shaft 46. An operating arm 80 for the rheostat is supported upon and insulated from the shaft 46 by means of a collar 82 to provide operation of the rheostat by the relative movement of the disc 42 and the shaft M5.- The resistance element I8 and the operating arm 80 are connected by means of conductors 8d and 86 to slip rings 88 and 99, respectively. The slip'rings 88 and 90 aremounted upon and insulated from the plate 42 and are insulated from each other by a band of insulating material 82. Suitable brush members 94 and 96 are positioned to maintain contact with the slip rings 88 and 99.

The system for controlling the speed of the motor 28 so as to rotate the slip ring 24 at the speed of rotation of the roll I8 is best illustrated in Fig. 3, :in which the motor 28, the slip rings 88 and 98, the brushes 94 and 96 and the rheostat elements I8 and 8!] are illustrated diagrammatically. The armature of the motor 28 is connected to any suitable source of direct current power of selectively adjustable potential, indicated by the conductors A--B, by the conductors 98 and I00. The field winding I82 of the motor 28 is connected in series circuit relation with an adjustable rheostat I84 and the rheostat 38 'm a circuit which extends from the conductor C of any suitable source of direct current of substantially constant potential indicated by the conductors CD, to the field winding I92, the conductor I08, the rheostat I04, the conductor III], the brush 94, slip ring 88, conductor 84, the rheostat operating arm 80, the rheostat resistance element I8, the conductor 86, slip ring 90, brush 96 and the conductor l I2 to the conductor D. The source of potential indicatedby the conductors AB may be a common source from which the motor 28 and the drive motors, (not shown) for pulling the strip I6 through the contact rolls I8 and 28 are energized. This permits simultaneous selective adjustment of the speeds of the strip and contact rolls and the motor 28 by armature voltage control in the well known manner, the

source of potential indicated by the conductors CD being used only for the regulation of the speed of the motor 28 by field control.

In the operation of the device, as the strip I6 is pulled through the rolls I8 and 20, it will cause the rolls to rotate and the motor 28 will cause the slip ring 25 to rotate at substantially the speed of the rolls. Sufficient slack is left in the conductors 22 to permit a limited relative rotation of the slip ring 25 and. the roll I8, so that there will be no actual mechanical power transmitting connection between the roll I8 and the slip ring 24, thus preventing the strip I6 from transmitting through the roll I8 the power necessary to supply the brush friction load on the slip ring 24. In the event that the motor 28 causes the slip ring 2Q to rotate at a speed lower than the speed of the roll I8, the rheostat operatingar n 8U willbe moved counter-clockwise, as

viewed in Fig. 3, to increase the efiective resistance of the rheostat resistance element I8; thus causing a decreased excitation of the motor 28 and a corresponding increase of the motor speed.

Similarly, in the event that the slip ring 24 rotates at a higher speed than that of the roll I8, the rheostat 38 will be automatically adjusted to decrease the speed of the motor 28.

The generator I I in Fig. l supplies power to the strip I6 by means of the conductors H4 and H6 which connect the opposite terminals of the generator I4 with the brushes of the current transfer devices I0 and I2, respectively. The current transfer devices I0 and I2 complete the conducting path to the strip I6 through their contact rolls as explained in the description of the apparatus of Fig. 2 of the drawings, and the strip I8 will be heated by the current flow therethrough as it passes between the adjacent contact roll stands.

Separate motors are provided for driving each of the slip rings 28 because different speeds of rotation of the slip rings may be necessary in the event that there is a difference in the diameters of the'contact rolls.

Any source of current for heating the strip I6 may be provided, the direct current generator I4 being merely illustrative; thus an alternating current generator would serve the purpose equally as well.

It is to be understoodthat any suitable means for maintaining the desired speed relation between the slip ring 25 and the contact roll I8 may be provided, the one shown and described herein being merely illustrative.

It is to be further understood that the system hereinbefore described is not limited to the transfer of current to contact rolls and strip material for the purpose of heating the material, but may beused to conduct current-to a strip for any other purpose.

It will be seen that I have provided a current transfer system which shall function to conduct current to a moving strip of material as it is pulled between the rolls of adjacent contact roll stands, and which shall function to supply the necessary brush friction power for the system without imposing this brush friction load upon the strip as it is pulled through the device.

In compliance with the requirements of the patent statutes, I have shown and described herein the preferred embodiment of my invention. It is to be understood, however, that the invention is not-limited to the precise construction shown and described, but is capable of modification by one skilled in the art, the embodiment herein shown being merely illustrative of the principles of my invention.

I claim as my invention:

1. In a system for transferring current between a current source and a rotatable element, cooperating brush and slip ring members, one of said'members being rotatable and the other being stationary and electrically connected to the current source, means including flexible conductorselectrically connecting the rotatable one of said members to the rotatable element and secured to said rotatable member and said rotatable'element, a motor for driving said rotatable member,and control means for said motor for causing said motor responsive to the relative displacement of said rotatable member and said rotatable element to rotate'the rotatable member at the speed of said rotatable element.

; 2. In-a system for applyinganrelectrical po- 7 conductors extending between and secured to said rotatable member and its associated roll, a drive motor for each of said rotatable members responsive to the relative displacement of its associated rotatable member and associated roll, and control means for each of said motors for causing each of said motors to rotate its associated rotatable member at the speed at which its associated roll is being rotated by the strip.

3. In a system for applying an electrical potential to a moving strip of material, two pairs of rolls of electricity conducting material spaced along the strip, the rolls of each pair being disposed to bear upon the strip as it passes therebetween and to be rotated by the moving strip, a set of cooperatingbrush and slip ring members associated with each of said rolls, one of each of said sets of members being rotatable and the other being stationary, means electrically connecting the rotatable one of each of said sets of members to its associated roll, a drive motor for each of said rotatable members, control means for each of said motors for causing each of said motors to rotate its associated slip ring at the speed at which its associated roll is being rotated by the strip, said control means comprising a rheostat associated with each of the motors and connected to control the speed of the motor, and means for actuating each of said rheostats in accordance with the angular displacement between its associated roll and rotatable member.

4. In a system for applying an electrical potential to a moving strip of material, two pairs of rolls of electricity conducting material spaced along the strip, the rolls of each pair being disposed to bear upon the strip as it passes therebetween and to be rotated by the moving strip, a set of cooperating brush and slip ring members associated with each of said rolls, means mounting each of said slip rings substantially coaxially with its associated roll, means electrically connecting each of said slip rings with its associated roll including flexible conductors extending substantially parallel with the axis of the rolls and permitting limited relative angular displacement of the slip ring and the roll, a drive motor for each of said slip rings, control means for each of said motors responsive to the relative angular displacement between its associated slip ring and roll for causing the slip ring to rotate at substantially the speed of rotation imparted to the roll by the moving strip, and means applying an electrical potential between the brushes associated with one pair of rolls and the brushes associated with the other pair of rolls.

5. In a system for applying an electrical potential to a rotating roll, a slip ring disposed substantially coaxially with the roll, stationary brush means disposed to engage said slip ring and connected to be energized by the electrical potential, means electrically connecting said slip ring with the roll including flexible conductors extending substantially parallel with the axis of the roll and permitting limited relative angular displacement between the slip ring and the roll, a drive motor for said slip ring, and control means for the motor responsive to the relative angular displacement of the roll with respect to said slip ring for causing the motor to rotate the slip ring at substantially the speed of rotation of the roll.

CLARENCE LYNN. 

